Background This study investigated whether a novel multi-injection intertransverse process block could provide non-inferior analgesia and recovery quality following major breast cancer surgery compared with the multi-injection thoracic paravertebral block.

Methods Eighty-eight females who underwent mastectomy plus sentinel or axillary lymph node dissection were randomized to receive either intertransverse process block or thoracic paravertebral block, both performed at T2–6 with 5 mL of 0.5% ropivacaine per level. The primary outcome was the worst resting pain score (11-point Numerical Rating Scale) within 30 min in the recovery room. The secondary outcome was recovery quality (15-item quality of recovery scale) 24 hours after surgery, which was tested following a gatekeeping procedure.

Results The worst resting pain scores were 0 (0, 1) in the intertransverse process block group vs 0.5 (0, 2) in the thoracic paravertebral block group, with a median difference of 0 (95% CI 0 to 0); the upper 95% CI limit was lower than the prespecified non-inferiority margin of 1 point (non-inferiority p<0.001). Aggregate scores of recovery quality at 24 hours postoperatively were 137.5 (126.5, 142.8) and 137.5 (127.8, 145.0) for the intertransverse process and thoracic paravertebral block groups, respectively, with a median difference of −1 (95% CI −6 to 3); the lower 95% CI limit was larger than the prespecified non-inferiority margin of −8 (non-inferiority p=0.006).

Conclusions Compared with a multi-injection thoracic paravertebral block, the multi-injection intertransverse process block provided non-inferior analgesia within 30 min in the recovery room and recovery quality at 24 hours following major breast cancer surgery in females.

Trial registration number ChiCTR2000037963.